Tuyere arrangement in cupola furnaces



May 6, 1952 H. A. REECE TUYERE ARRANGEMENT IN CUPOLA FURNACES Filed June15, 1950 FIG. 1

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INVENTOR. HERBERT A. Reece BY ATTORNFY Patented May 6, 1952 TUYIJREARRANGEMENT IN CUPOLA FURNACES Herbert A. Reece, Cleveland Heights, OhioApplication June 15, 1950, Serial No. 168,247

This invention relates, as indicated, to tuyrc arrangement in cupolafurnaces and the like.

Many and varied types and arrangements of tuyeres in cupola furnaceshave heretofore been used and proposed, in attempts to obtain improvedcombustion, greater penetration of the blast, and to decrease or lessenthe tendency toward formation of bridges or scafiolds (mixtures of slag,iron and coke) in the cupola furnace. Some of these types and sizes oftuyres are shown on page of Melting Iron in the Cupola, by J. E. Hurst,published by The Penton Publishing Company in 1929.

As air (02) enters the cupola shaft from the ports or tuyres, it comesinto contact with the incandescent carbon of the coke in the cupolashaft. When the velocity of the air (02) is high, that is to say, whenhigh velocity tuyres are used, incomplete combustion takes place, withunused oxygen present, the oxygen being carried higher in the meltingzone, with greater time of contact between the droplets of molten iron.When the velocity of the air is low, that is to say, when low velocitytuyres are used, a rapid formation of CO2 takes place, the droplets ofiron are subjected to this 002, and the heat necessary for melting theiron is dissipated in the coke bed, rather than in the melting zone ofthe shaft. This leads to rapid deterioration of the coke bed, withconsequent changes in the Belden curve (see Bulletin 54-U. S. Bureau ofMines, 1913, and pages 34 and 35 of Gray Cast Iron, by John W. Bolton,published by the Penton Publishing Company in 1937) occurring during theheat. Thus, with both high velocity and low velocity of the air enteringthe shaft, the problem of efficient melting of the iron is present.Equalized velocity tuyeres have the disadvantage of rapid burn out ofthe lining of the cupola in specific areas directly above the coverplates.

Efiicient melting involves the problem of having the gases CO2 and COpresent in substantially equal proportions at the melting zone, withfree oxygen substantially absent. The CO2 content of the gases isrequired to furnish the required number of B. t. u.s for impartingtemperature to the iron melted, while the CO content of the gases isrequired to furnish absorbable carbon for the iron being melted. Theoptimum condition, in addition to this, is to have the smallest amountof 02 present at the least height above the tuyres.

I have discovered that the aforesaid disadvan- 3 Claims. (01. 266-30)tages and undesirable efiects of high and low velocity air input intothe shaft can be eliminated or minimized to a great extent, and theefiiciency of cupola melting greatly increased, by utilizing acombination of high and low velocity air input in a manner designed toaccomplish the following results:

1. Less bridging of the cupola. 2. Better combustion. 3. Betterpenetration of the blast.

I accomplish these results by utilizing a novel arrangement of tuyeresin the walls of the cupola shaft, as will hereinafter appear, referencebeing had to the accompanying drawing, wherein is shown a typicalembodiment of the invention. In said annexed-drawings,

Fig. 1 is a fragmentary cross-sectional view of a cupola furnace,showing one arrangement of the tuyeres according to the invention, and

Fig. 2 is a development, on an enlarged scale, of the entire inner wallof the cupola shaft shown in Fig. 1, showing the arrangement of theemergent ends of the tuyre openings.

Referring more particularly to the drawings, reference numeral Idesignates the shell of a cupola furnace, having a refractory lining 2,a wind box 3 surrounding the lower porton of the shell, and adapted toreceive air from a blast pipe 4.

The air thus received in the windbox 3, is blown into the shaft througha series of tuyres, the emergent openings of which are designated 5 and6, respectively, these openings being arranged in spaced relation aboutthe entire circumference of the inner wall or lining of the shaft.

In this specific instance, the total number of tuyre openings is eight,and the four openings 6 are arranged alternately with and in staggeredrelation to the four openings 5, with a horizontal plane passing throughall of the tuyres. For practical purposes, the tuyres or openings 5 are8 inches in height, and the tuyeres or openings 5 are 4 inches inheight, with a horizontal plane XX intersecting all of the openings.From this plane, the tuyres 5 extend downwardly and the tuyeres 6upwardly. This arrangement and size of tuyres is used in lieu of anormal arrangement of tuyeres in which all of the tuyeres are of 6inches in height, and disposed in side by side relation.

The larger tuyeres 5 provide a high velocity flow, which is contrary towhat those skilled in this art would normally expect, while the smallertuyeres 6 provide a low velocity flow of air into the cupola furnace.The total tuyere area has been found to produce the best results when itis equivalent to 29% of the area of a 36 inch cupola, but this varieswith the size of the cupola and is not a prime consideration, insofar asthis invention is concerned.

It is presumed that the lag of gas obtained by the high velocity air,which has 4 inches farther to travel than the low velocity air, performsa buffing action for just a suificient length of time to accomplish abetter admixture in the presence of the incandescent carbon in the coke,with consequent better penetration of the oxygen to the center of thecupola, and a more even velocity throughout the cupola shaft than isobtained when all of the tuyeres, regardless of area, are in the samehorizontal plane (nonstaggered). The two speeds of air, with actualconfluence to create the time lag, provides a controlled differentialvelocity. Thus, while we may have a linear flow of air at the highervelocity through the tuyeres 5 of 21 linear feet per second, it willmeet the lower velocity air from tuyeres 5 which has a flow of 12 linearfeet per second, and from this confluence of air, we not only obtain aretarded linear flow and time lag, but a dissipation of the air currentsas well.

The air entering a cupola, with a conventional or normal arrangement oftuyeres, has a higher velocity at the walls of the cupola than in thecenter of the cupola, due to the resistance imposed by the cupolacharge. The present arrangement of tuyeres in staggered relation," witha horizontal plane passing through all of the tuyeres, apparentlyeliminates this difference in velocity, in the melting zone, at least.

The new arrangement of tuyres is not to be confused with an arrangementof tuyres, in which an auxiliary or second row of tuyeres is disposeddirectly above or in staggered relation to a first row of tuyeres. Insuch an arrangement, the upper row of tuyres, even when staggered withrespect to the first row of tuyeres,

is not so arranged that a single horizontal plane can intersect bothrows of tuyeres.

Although the tuyere arrangement has been described with reference to acircular cupola furnace, it will be understood that substantially thesame arrangement with like results, can be used in connection withcupola furnaces of square or rectangular cross-section.

It is to be understood that various changes in the size of tuyereopenings, their arrangement, and the extent to which they are instaggered relation with each other, may be made, without substantialloss of the advantages resulting from the arrangement, as described, andwithout departing from the scope of the appended claims.

Having thus described my invention, I claim:

1. In a cupola furnace, an arrangement of tuyeres comprising a row ofhorizontally-spaced tuyeres of predetermined height and through whichair passes into the cupola in a substantially horizontal direction, anda second row of horizontally-spaced tuyeres of less height than those ofthe first row, and through which the air passes into the cupola in asubstantially horizontal direction, the tuyeres of the second rowalternating with the tuyeres of the first row, all of the tuyeres beingintersected by a common horizontal plane, with portions of the tuyeresof the second row being disposed above a horizontal plane passingthrough the upper edges of the tuyeres in the first row.

2. A cupola furnace, as defined in claim 1, in which all of the tuyresare of substantially the same width.

3. A cupola furnace, as defined in claim 1, in which the tuyeres of thesecond row are substantially half the height of the tuyeres in the firstrow.

HERBERT A. REECE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 634,645 Dougherty May 14, 186766,962 Hotchkiss July 23, 1867 172,836 Voisin Feb. 1, 1876 240,135Ibrugger Apr. 12, 1881 324,623 Whiting Aug. 18, 1885 1,205,568 Ross Nov.21, 1916 1,640,251 Poumay Aug. 23, 1927 FOREIGN PATENTS Number CountryDate 20,924 Great Britain Mar. 26, 1914

